Genomics is identifying the genes responsible for all human functions and diseases. With 80,000 genes in the human genome, the thousands of genes involved in development, stature, intelligence, and other features of a human being are being defined. Humans suffer from hundreds of inherited and infectious diseases, and the genes involved in such are also being identified. Proteins encoded by all these genes are targets for therapeutic drugs. However, drugs that can be applied to human function and disease will not simply emerge from genomic information. Conventional drug development for a single disease is a lengthy, tedious and extremely expensive process. Technologies that eliminate the major hurdles facing drug development in the post-genomic era would be of substantial value.
The present invention provides a method for producing a mass-coded set of chemical compounds having the general formula X(Y)n, where X is a scaffold, each Y is, independently, a peripheral moiety, and n is an integer greater than 1, typically from 2 to about 6. The method comprises selecting a peripheral moiety precursor subset from a peripheral moiety precursor set. The subset includes a sufficient number of peripheral moiety precursors that at least about 50, 100, 250 or 500 distinct combinations of n peripheral moieties derived from the peripheral moiety precursors in the subset exist. The subset of peripheral moiety precursors is selected so that at least about 90% of all possible combinations of n peripheral moieties derived from the subset of peripheral moiety precursors have a molecular mass sum which is distinct from the molecular mass sums of all of the other combinations of n peripheral moieties. The method further comprises contacting the peripheral moiety precursor subset with a scaffold precursor which has n reactive groups, each of which is capable of reacting with at least one peripheral moiety precursor to form a covalent bond. The peripheral moiety precursor subset is contacted with the scaffold precursor under conditions sufficient for the reaction of each reactive group with a peripheral moiety precursor, resulting in a mass-coded set of compounds of the general formula X(Y)n.
In another embodiment, the invention provides a method of identifying a member or members of a mass-coded combinatorial library which are ligands for a biomolecule, for example, a protein or a nucleic acid molecule, such as DNA or RNA. The method comprises the steps of (1) contacting the biomolecule with the mass-coded molecular library, whereby members of the mass-coded molecular library which are ligands for the biomolecule bind to the biomolecule to form biomolecule-ligand complexes and members of the mass-coded library which are not ligands for the biomolecule remain unbound; (2) separating the biomolecule-ligand complexes from the unbound members of the mass-coded molecular library; (3) dissociating the biomolecule-ligand complexes; and (4) determining the molecular mass of each ligand to identify the set of n peripheral moieties present in each ligand.
In a further embodiment, the invention provides a method for identifying a member or members of a mass-coded molecular library which are ligands for a biomolecule and bind to the biomolecule at the binding site of a ligand known to bind the biomolecule (a known ligand). The method comprises the steps of: (1) contacting the biomolecule with the mass-coded molecular library, so that members of the mass-coded molecular library which are ligands for the biomolecule bind to the biomolecule to form biomolecule-ligand complexes and members of the mass-coded library which are not ligands for the biomolecule remain unbound; (2) separating the biomolecule-ligand complexes from the unbound members of the mass-coded molecular library; (3) contacting the biomolecule-ligand complexes with a ligand known to bind the biomolecule, to dissociate biomolecule-ligand complexes in which the ligand binds to the biomolecule at the binding site of the known ligand, thereby forming biomolecule-known ligand complexes and dissociated ligands; (4) separating the dissociated ligands and biomolecule-ligand complexes; and (5) determining the molecular mass of each dissociated ligand to identify the set of n peripheral moieties present in each dissociated ligand.
In a yet further embodiment, the invention provides a method for identifying a member or members of a mass-coded combinatorial library which are ligands for a first biomolecule but are not ligands for a second biomolecule. The method comprises the steps of: (1) contacting the first biomolecule with the mass-coded molecular library, whereby members of the mass-coded molecular library which are ligands for the first biomolecule bind to the first biomolecule to form first biomolecule-ligand complexes and members of the mass-coded library which are not ligands for the first biomolecule remain unbound; (2) separating the first biomolecule-ligand complexes from the unbound members of the mass-coded molecular library; (3) dissociating the first biomolecule-ligand complexes; (4) determining the molecular mass of each ligand for the first biomolecule; (5) contacting the second biomolecule with the mass-coded molecular library, whereby members of the mass-coded molecular library which are ligands for the second biomolecule bind to the second biomolecule to form second biomolecule-ligand complexes and members of the mass-coded library which are not ligands for the second biomolecule remain unbound; (6) separating the second biomolecule-ligand complexes from the unbound members of the mass-coded molecular library; (7) dissociating the second biomolecule-ligand complexes; (8) determining the molecular mass of each ligand for the second biomolecule; and (9) determining which molecular masses determined in step (4) are not determined in step (8). This provides the molecular masses of members of the mass-coded combinatorial library which are ligands for the first biomolecule, but are not ligands for the second biomolecule.
In another embodiment, the method for identifying a member or members of a mass-coded combinatorial library which are ligands for a first biomolecule but are not ligands for a second biomolecule comprises the steps of: (1) contacting the second biomolecule with the mass-coded molecular library, so that members of the mass-coded molecular library which are ligands for the second biomolecule bind to the second biomolecule to form second biomolecule-ligand complexes and members of the mass-coded library which are not ligands for the second biomolecule remain unbound; (2) separating the second biomolecule-ligand complexes from the unbound members of the mass-coded molecular library; (3) contacting the first biomolecule with the unbound members of the mass-coded molecular library of step (2), whereby members of the mass-coded molecular library which are ligands for the first biomolecule bind to the first biomolecule to form first biomolecule-ligand complexes and members of the mass-coded library which are not ligands for the first biomolecule remain unbound; (4) dissociating the first biomolecule-ligand complexes; and (5) determining the molecular mass of each ligand for the first biomolecule. Each molecular mass determined corresponds to a set of n peripheral moieties present in a ligand for the first biomolecule which is not a ligand for the second biomolecule.
In yet another embodiment, the present invention relates to a method for identifying a member of a mass-coded combinatorial library which is a ligand for a biomolecule and assessing the the effect of the binding of the ligand to the biomolecule. The method comprises the steps of: contacting the biomolecule with the mass-coded molecular library, whereby members of the mass-coded molecular library which are ligands for the biomolecule bind to the biomolecule to form biomolecule-ligand complexes and members of the mass-coded library which are not ligands for the biomolecule remain unbound; separating the biomolecule-ligand complexes from the unbound members of the mass-coded molecular library; dissociating the biomolecule-ligand complexes; determining the molecular mass of each ligand to identify the set of n peripheral moieties present in each ligand. The molecular mass of each ligand corresponds to a set of n peripheral moieties present in that ligand, thereby identifying a member of the mass-coded combinatorial library which is a ligand for the biomolecule. The method further comprises assessing in an in vivo or in vitro assay the effect of the binding of the ligand to the biomolecule on the function of the biomolecule.
The method of the invention allows rapid production of mass-coded combinatorial libraries comprising large numbers of compounds. The mass-coding enables the identification of individual combinations of scaffold and peripheral moieties by molecular mass. The libraries prepared by the method of the invention also allow the rapid identification of compounds which are ligands for a given biomolecule.